Gabriel_Dirac

Gabriel Andrew Dirac (13 March 1925 – 20 July 1984) was a Hungarian-British mathematician who mainly worked in graph theory. He served as Erasmus Smith's Professor of Mathematics at Trinity College Dublin from 1964 to 1966. In 1952, he gave a sufficient condition for a graph to contain a Hamiltonian circuit. The previous year, he conjectured that n points in the plane, not all collinear, must span at least

⌊
n

/

2
⌋

{\displaystyle \lfloor n/2\rfloor }
two-point lines, where

⌊
x
⌋

{\displaystyle \lfloor x\rfloor }
is the largest integer not exceeding

x

{\displaystyle x}
. This conjecture was proven true when n is sufficiently large by Green and Tao in 2012.